In the shipment of goods such as typewriters, video displays and the like, care must be taken to package such articles with sufficient protection against careless handling. One technique involves the formation of packings that are specifically shaped to fill a portion of the space between the articles and the container in which it is shipped.
One packaging technique involves a foam-in-place process wherein the article is placed in a container and a separator sheet material is tucked around the article. A polyurethane foam material is then poured into the space between the sheet and the container to fill the void and firmly support the article. Since such technique may result in the support of the article at sensitive areas where damage may result; hence, another packaging technique involves the preforming of foam packings that are shaped to fill selected voids in the space between the article and its container.
The preformed molded packings are made by using a plug having a shape that is generally representative of the article. The plug is mounted in the chamber of a mold box. A sheet material is then placed over the mold box opening and tucked into the cavities around the plug and over the inside surface of the lid. A vacuum is then formed between the sheet and the mold box so as to draw the sheet into the corners and various cavities around the plug in the box chamber. A foam is then poured over the sheet and the mold box lid is closed until the foam is cured. After curing the foam-in-place molded packing and sheet are removed from the box.
In another technique a mold plug projects from a platform and a polyethylene separator sheet is placed over it. A vacuum draws the sheet over the plug and a container with open flaps in which the article is to be shipped is placed over the plug to seat on the platform and form a mold with the plug. The foam is then injected into the container to form a molded packing directly in the container in which an article is to be shipped.
The time required to make a molded packing is a function of the time needed to insert the sheet material, pour the foam, await its cure and remove the sheet and plug from the completed packing. When a large number of molded packings need to be made, it becomes highly desirable to increase the speed of their manufacture.